= Shell Function =

<<TableOfContents>>

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== Declaration ==

A function is declared like:

{{{
myfunction() {
  :
}
}}}

A function's name must match `[a-zA-Z_][a-zA-Z0-9_]*`.

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== Usage ==

The above function would be called like:

{{{
myfunction "first argument" "second argument"
}}}



=== Arguments ===

Arguments passed to a function implicitly overwrite the [[Shell/Variables#Positional_Variables|positional variables]] as well as the [[Shell/Variables#Special_Variables|argument count variable]] (`$#`). All of these will be reset to the original values upon the function's return.

Note that `$0` is ''not'' overwritten.



=== Error and Return Codes ===

By default a function does ''not'' set the exit code. But it also does not clear the code. The final command in a function effectively sets the error code for the function as well.

The `return` builtin causes the function to return immediately with a specified exit code.

{{{
isdirectory() {
  if [ -d "$1" ]; then
    return 0
  else
    return 1
  fi
}

if isdirectory "$some_directory"; then
  :
fi
}}}



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CategoryRicottone